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Visitor II
November 3, 2025
Question

stm32 i2c transmitter mode flags doubt

  • November 3, 2025
  • 1 reply
  • 142 views

why need to monitor txe flag and btf flag to transfer data after each byte.

txe says data register is empty,

btf  and txe says need monitor after last byte. according to reference manual.

but my question is how should i know i get ack after sending 1 byte .in this case which should i check txe,btf.

if i check txe if txe==1 i send 2nd byte then how should i know i get ack for byte1.

if txe indicate about ack flag received/not ,then why should compulsory use btf flag at end of last byte to check wait untill btf==1 before stop condition.

 

 

 

 

 

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    1 reply

    Super User
    November 3, 2025

    > but my question is how should i know i get ack after sending 1 byte .in this case which should i check txe,btf.

    The reference manual goes over the details here.

    If you only want to send 1 data byte, BTF will be set after the first byte is sent and you need to generate a stop condition. TXE will also be set but it is not what you want to check.

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